1. Field of the Invention
The present invention relates to a printing apparatus and a printing method.
2. Description of the Related Art
In recent years, printing apparatuses are capable of double-sided printing for printing on both sides of a paper sheet to save paper resources.
Among the printing apparatuses that perform such double-sided printing is a printing apparatus that automatically reverses a sheet, and performs automatic double-sided printing on both sides of the sheet in sequence of pages. Moreover, there is a printing apparatus that performs manual double-sided printing by sequentially printing only images of odd pages of print data on one side of sheets and discharges onto a discharge tray. When the printing of the odd pages of the print data is finished, the other side of the sheets discharged on the discharge tray is set manually on a feed tray, a manual feed tray, and the like, as the print side. When instructed to print, the printing apparatus sequentially prints even pages of the print data on the other side of the sheets already printed on one side.
Japanese Patent Application Laid-Open No. 2006-18464 discloses a conventional printing apparatus that has such a manual double-sided printing function, and continuously prints one side of sheets while controlling a sequence of pages of print data. Upon completion of printing on one side of all the sheets, the other side of the sheets is set on the feed tray or the like as the print side. When instructed to print, the printing apparatus continuously prints the other side.
However, with the conventional printing apparatus, as shown in FIG. 10, regardless to the number of pages of the print data, all the pages to be printed are arranged to one side and the other side for double-sided printing. After one side of all sheets is continuously printed and the sheets are discharged on a discharge tray, the other side of the sheets already printed on one side is set on a feed tray as the print side and continuously printed. Accordingly, if the number of sheets printed with the print data does not exceed the maximum dischargeable number of sheets of the discharge tray, the print data can be printed on the sheets in the sequence of one side of a sheet, the other side, one side, . . . (continued) properly to both sides thereof in the sequence of the pages. However, if the number of sheets printed by the print data exceeds the maximum dischargeable number of sheets of the discharge tray, the sheets already printed on one side overflow and slide out from the discharge tray. Accordingly, problems occur such as the page sequence of the sheets already printed on one side gets messed up, making it unable to perform double-sided printing in the proper page sequence. Even if the pages are printed, it takes time to align pages, which causes poor workability. Moreover, the already-printed sheets slid out from the discharge tray may get lost or stolen. Although the security of information has been demanded in recent years, it may become a security hole.